For a better understanding and improved management of human malignancies, more needs to be learned about the basic control mechanisms in human tumor cells, particularly the regulation of gene expression and cell growth. Cloned cultured human cervix carcinoma cells offer several advantages for some of these studies, since most human malignancies are epithelial. Our results on the inhibition of the synthesis of low molecular weight RNA species C and D by ultraviolet radiation in human carcinoma cells are compatible with models in which: a) these RNAs are synthesized as primary transcripts that may be as much as 25 times longer than the detected precursors of these RNA species; and b) these transcripts may even be polycistronic for a given low molecular weight RNA. These, plus other unexpected findings related to the genes for these RNAs and their transcripts, suggest that both the genes for C and D RNA and their transcripts deserve to be studied in detail. The first objective of this project is to clone DNA fragments containing the genes for RNA species C and D, from cultured human carcinoma cells, using recombinant DNA technology. Our next goal is to carry out a detailed study of the organization of these cloned genes and their flanking sequences, by restriction endonuclease mapping, electron microscopic heteroduplex analysis, and DNA sequencing. The third objective is to isolate segments from these cloned DNA fragments, obtained by appropriate restriction cleavages, and to purify (at least partially): a) gene sequences for C or D RNA; and b) their flanking spacer sequences. The resulting gene and spacer fragments will then be used separately as probes for the study of their transcripts.